1. Field of the Invention
The present invention relates generally to structure monitors, and, more particularly, to a portable device for monitoring structures for movement, especially in emergency or damage situations, and alarming persons in the vicinity of impending danger or structure collapse.
2. Description of the Related Art
In the related art, many methods of monitoring structures, such as walls, roofs, or bridges, for motion or structural deflection are known. For example, in U.S. Pat. No. 5,404,132, issued in the name of Canty et al., a deflection monitoring system is disclosed utilizing a series of laser beams at the perimeter of a support structure for the effects of external stress factors. Deflection in a support structure is registered when the path of the beams between the laser and a receiver is broken, hopefully by a deflection in the monitored structure.
Also known is U.S. Pat. No. 5,289,434, issued in the name of Berni, in which a retro reflector apparatus for remote seismic sensing is disclosed in which a polarizing beam splitter splits a sensing laser beam so as to be later compared for differences in vertical seismic motion at a remote site.
Another illustration of the related art appears in U.S. Pat. No. 4,899,997, issued in the name of Tomiolo, wherein a process and device for measuring and processing the displacements between two or more points in structures, buildings, machinery or the like is disclosed. Once again, a laser ray directed toward a number of targets is utilized with this process and device.
And finally, in U.S. Pat. No. 4,843,372, issued in the name of Savino, a bridge sway and deflection detection system is disclosed which once again utilizes a laser gun and a receiver, in conjunction with a mirror system and a plurality of aperture plates in order to monitor and detect for swaying and deflection in a bridge.
Although many of these related disclosure can be adapted to monitor the motion of structures, none can provide a portable device for monitoring structures for movement, especially in emergency or damage situations, and alarming persons in the vicinity of impending danger or structure collapse. Nor can any of these related disclosure provide the precision and reliability of computer monitoring and image comparison. Consequently, a need has been felt for providing an apparatus and method which overcome the problems associated with manually monitoring a damaged structure in danger of collapsing, without the limitations of a permanently installed system.